Updated fastlane_core dependency

Author: KrauseFx

deliver.gemspec

@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.add_dependency 'fastlane_core', '>= 0.15.1' # all shared code and dependencies
+  spec.add_dependency 'fastlane_core', '>= 0.15.3' # all shared code and dependencies
   spec.add_dependency 'credentials_manager', '>= 0.3.0'
   spec.add_dependency 'nokogiri', '~> 1.6.5' # parsing and updating XML files
   spec.add_dependency 'fastimage', '~> 1.6.3' # fetch the image sizes from the screenshots